Gage for indicating vacuum.



INVENTOR ATTORNEY WITNESSES Patented Dec. 14, 1915. r 2 SHEETSSHEET 2.

INVENTOR WITNESSES ATTQRNEY -11 PAT con.

SIDNEY w. FARNSWORTH, or PITTSBURGH, PENNSYLVANIA, ASSIGNOR 'ro WESTING- HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION or rnnusrn- VAN 1A.

GAGE FOR INDICATING VACUUM.

To all whom it may concern:

Be it lmown that I, SIDNEY W. FARNS- WORTH, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have 1nvented a new and useful Improvement in Gages for Indicating Vacuum, of which the following is a specification.

This invention relates to vacuum indicators of the type wherein a high-potential Geissler-tube discharge is set up in a portion of the vacuum to be tested and the degree of evacuation is judged by the color of the discharge.

The object of the invention is to produce a device of the character specified which shall be simple .and economical in construction, easily applied to the container wall and capable of use indefinitely wlthout developing leaks.

Referring to the accompanying drawing,

'Figure 1 is a view partially in elevation and partially in section of my vacuum indicator; Fig. 2 is a plan view of the same; Figs. 3 and 4 are views mainly in plan and 1n elevation, respectively, but partially in sec tion, of a modification of my device; and Fig. 5 is a view partially in section, and partially in elevation of another modification.

1 represents the wall of a containing vessel which is to be evacuated to a very high degree by any suitable means, and used, for example, as the container of a mercury arc rectifier. Wall 1 is preferably of metal but may be of any suitable impervious and opaque material, such, for example, as glazed porcelain or lava.

2 representsone of the anodes of the rectifier, current being supplied thereto by a conductor 3. v

4 denotes an opening in the container wall into which is ground, or otherwise tightly fitted, the open end of a tubular transparent member 5. In order to insure that the joint between the parts 1 and 5 shall, at all times, remain tight, the container wall is provided with a retaining ring 6 and, in the annular space between ring 6 and member 5, is placed a suitable sealing liquid 8, such, for example, as mercury. Whilev I have shown the member 5 in an upright position, so that the mercury 8 is retained in place by gravity, a cover may be provided above the mercury in order that the device may be tilted in any position, if desired. The upper end of memnication with the Specification of Letters Patent. Patented Deg, 14, 31915, Application filed March 21, 1914. Serial No. 826,243.

' her 5 is closed, and, upon the surface thereof,

is placed a condenser type electrode 9 of some conducting material, such, for example, as tin foil. Such condenser electrodes are old and well known in the art and need no detailed description. While I have shown the condenser electrode as mounted on the end of member 5, it may take the form of a band upon any portion thereof without departing from the spirit of my invention. Connected between electrode 9 and the wall of the container, when the latter is of conducting material, is any source of high-potential currents, such, for example, as a step-up transformer 10.

Having thus described my invention in its preferred form, I will now proceed to a description of the operation thereof. Since the mterior of member 5 is in direct commucontainer, its degree of evacuation Will vary directly therewith. Accordingly, as the pumping out of the container continues and the vacuum rises, the discharge from the source 10, taking place between the electrode 9 and the wall of the opening 4, causes the tubular member 5 to be filled with luminescence, as is well known in the art. By once calibrating the device by comparison with an ordinary vacuum gage and noting the color of the luminescence for each degree of evacuation, a device is obtained which simply, readily and without adjustment enables one tion of the vacuum within the container. When pumping out containers-of this type, it is customary to pass a heavy current therethrough, by means of the regular electrodes, in order that the occluded gases may .be driven off from the walls and electrodes. Since the light of this heavy discharge would completely mask the luminescence within member 5, I provide a shielding member 12 which is directly in front of the opening 4 and prevents the direct passage of light thereinto from the interior of the container. Member 12 is suitably spaced from the wall by its supports 13 so that free passage between the lnterior of member 5 and the interior of the container is not interfered with.

Referring to Figs. 3 and 4, the container is shown as made of insulating material, such as lava or porcelain, but it might equally well be constructed of metal. The tubular, light-transmitting, vacuum-indicating member 5 is'ground into the wall 1 of the conto judge of the condi- .view of the tubular member 5 may b b.

tained.

The shield 18 is carried by a base member 20 that is clamped to the wall of the container by any suitable means, such, for example, as bolts 21. The outer end of the shield member 18 is closed by a cap 22,

preferably composed of conducting material. Mounted on the inner surface of the cap 22, is a spring member 23 that is adapted to make contact with the condenser terminal 9 of the indicating tube 5 and to supply it with current.

Current is supplied to the cap 22 by any suitable means, such, for example, as the binding post 25, and current is supplied to the inner end of the tubular member 5 by means of the sealing mercury 26, the base member 20 and any suitable wire terminal, such, for example, as 27 In order to prevent short circuiting between the two current terminals, it' is necessary that the shielding member 18 be of some insulating material such, for example, as fiber, micarta, molded mica or the like. If the. wall of the container is of conducting material, it is unnecessary to depend upon the condenser action of the mercury 26 to provide the inner electrode but current will flow directly from terminal 27 to the wall of the container and thence into the open end of the tubular member 5.

Referring ,to the form of my device shown in Fig. 5, the tubular member 5 of suitable light-transmitting material is provided with a T- haped' head 29, and each end of the head 29 is provided with a condenser-type terminal member 30, these terminal members being provided with current from any suitable source. With this form of my device, it is unnecessary to connect the exciting circuit of. the indicating tube in any way to the wall of the container or to the interior thereof. In this way, complete independence of the circuits of the device is secured.

Having thus described my device in its preferred form what I claim is:

1. The combination with a container having an opening in the wall thereof, a tubular member of transparent material having one end sealed over said opening and having its other end. closed, and a condenser-type electrode applied to the transparent wall at a distance from the container, of a source of high-potential currents connected between the condenser terminal and a terminal member operative in the evacuated space.

2. The combination with a conducting container, having an opening in the wall end sealed over said opening thereof, a tubular member of transparent material having one end sealed over said opening and having its other-end closed, and a condenser-type electrode applied to the transparent wall at a distance from the container, of a source of high-potential currents connected between the condenser terminal and the wall of the container.

3. The combination with a container having an opening in the wall thereof, a tubular member of transparent material having one end sealed over said opening by a liquid seal and having its other end closed, and a condenser-type electrode applied to the transparent wall at a distance from the container, of a source of high-potential currents connected between the condenser terminal and a conducting member exposed to the interior of the container.

4:. The combination with a container having an opening in the wall thereof, a tubular member of transparent material having one and having its other endclosed, and a con enser-type electrode applied to the end of the tubular member at a distance from the container, of a source of high-potential currents connected between the condenser terminal and a conducting member exposed to the interior of the container.

5. The combination with a conducting container having an opening in the wall thereof, a tubular member of transparent material having one end sealed over said opening and having its other end. closed, and a condenser-type electrode applied to the closed end of the tubular member, of a source of high-potential currents connected I between the condenser terminal and the wall of the container.

6. The combination with a container having an opening in the wall thereof, of a tubu ar member of light-transmitting material having one end sealed over said opening and having its other end closed, means for causing a high-potential discharge within said tubular member, and means for shielding said tubular member from light produced within said container.

7. The combination with a container having an opening in the wall thereof, of a tubular member of light transmitting material having one end sealed over said opening and having its other end closed, and a perforated shade carried by the container and servlng meaeee $3 shield carrying a conducting member adgustand serving to rotect said tubular member 10 ed to make contact with the electrode 0 the from mechanica injury. tubular member. In testimony whereof, I have hereunto 9. The combination With a container havsubscribed my name this 13th day of March, 5 ing an opening in the Wall thereof, of a tu- 1914.

bular member of light-transmitting -mate- SIDNEY W. FARNSWORTH. rial having one end sealed over said open- Witnesses: ing and having its other end closed, and a E. E. ROBE,

perforated shield carried by the container B. B. HINEs. 

